Method of extracting sulfur from underground deposits



vMarch 5A, 195,7

METHOD DR EXTRACTING SULFUR FROM UNDERGROUND DEPosITs Filed April :5, 1953 F. M. NELsoNErAL 2,783,986

4 Sheets-Sheei'l l INVENTORS 5959 M /Vfl S0/V Armen/Ew;

March 5, 1957 F. M. NELSON ETAL 2,783,986

METHOD OF EXTRACTING SULFUR FROM UNDERGROUND DEPOSITS Filed April 3, 1953 4 Sheets-Sheet 2 INVENToRs FP50 M /l/'ZSO/V BY ARA/m0 E EMA/VEA March 5, 1957 F. M. NELSON Erm. 2,783,986

METHOD DR ExTRAcTING SULFUR FROM UNDERGROUND DRRosITs Filed April s, 195s 4 Sheets-Sheet 3 m TR L:

R s am R w D //v \\\\\\\\U\ /MNw/ DUUR A March 5, 1957 F. M. NELSON ErAl.

METHOD OF EXTRACTING SULFUR FROM UNDERGROUND DEPOSITS Filed April 3, 1953 4 Sheets-Sheet 4 INVENTORS M 5 M ,W QM P af. m Mz f f A Maf @M im METHOD F EXTRACTING SULFUR FROM UNDERGROUND DEPDSTS Fred M. Nelson, Houston, and Arnold F. Zemanek, Newgulf, Tex., assignors to Texas Gulf Sulphur Company, New York, N. Y., a corporation of Texas Application April 3, 1953, Serial No. 346,634 4 Claims. (Cl. 262-6) This invention relates to underground deposits.

Heretofore sulfur has been deposits by drilling vertically the deposit and by inserting concentric casings and an air line through the drilled hole and into the deposit. Thereafter hot water at a temperature suitable for melting the sulfur from the formation is introduced into the sulfur deposit, preferably through the outer casing. The hot water melts the sulfur in the deposit and it ows downwardly to the bottom of the casing. The molten sulfur is then extracted through the inner casing by means of air introduced through the air line.

In carrying out this operation, the sulfur is extracted from a generally inverted, conical area surrounding the casings.

Employing such a method, it is generally possible to extract about 4,000 tons of sulfur from a single well before exhaustion of the well in sulfur deposits of about one hundred feet in thickness. After the extraction of this much sulfur, which can be accomplished by the expenditure of about 600 gallons of water per minute at 320 F., which will produce about 300 tons of sulfur a day in such a well, the water tends to ash up into the cap rock and is not effective to produce sufficient sulfur to warrant operation of the well.

Furthermore, it is very common to produce a rnechanical failure in such a well because of subsidence of the ground above the deposit directly above the point of extraction. Such subsidence is generally accompanied by a lateral shifting of the soil, which tends to shear the casings. Many times this lateral shifting of the ground, which may be as much as twenty feet, occurs during the first few days of operation of the well and many wells will fail before they have been in operation for ten days. in fact, most wells fail because of these mechanical failures before the formation is completely exhausted.

In addition to the mechanical failure, in many instances the subsidence of the ground and the collection of water in the area of subsidence causes damage to or loss of drilling equipment.

One object of the present invention is to overcome the aforesaid diiculties.

Another object is to provide a method of extracting sulfur in which mechanical failure due to the shearing of the casings is substantially eliminated.

Another object is to provide a method in which the casing is introduced through the ground above the deposit and into the deposit on a line substantially parallel with the line of future probable shifting due to subsidence of the earth so as to eliminate shearing o the casing.

Another object is to provide a method which is most economical in that in addition to longer life of the well, it is possible to achieve unexpectedly greater yields of sulfur for a given expenditure of hot water.

Another object is to provide a method in which the heating of the sulfur is accomplished with augreater length the extraction of sulfur from extracted from underground to and substantially through fates atent of casing with the attendant economy in heat, Water and equipment.

Another object is to provide a method which will prevent or minimize water ash-into the cap rock and overlying sediments of a formation, thereby effecting conservation of water with a resultant increase in operational eciency.

Another object is to provide a method which uses considerably less water to produce a ton of sulfur by more effectively heating and utilizing a greater volume of formation or connate water which is a particularly important point (with reference'to producing sulfur) in areas of limited Water supply and in which sulfur recovery per gallon of water is substantially higher than with vertical production techniques.

Another object is to provide a method by which a subsided or caved area 'can be mined efficiently.

Another object is to provide a method by which an area exhausted as concerns vertical production may be reworked with the recovery of a substantial amount of sulfur.

For the purpose of illustrating the invention, there are shown in the accompanying drawings ways of carrying it out which are at present preferred since they give desirable and satisfactory results. It `will be understood, however, that the invention may be used in various other ways and that the invention is not limited to the specific arrangement here shown and described.

In the drawings:

Fig. 1 is an elevational earth and through a sulfur vention is carried out; Fig. 2 is a top plan view of the well arrangement shown in Fig. l;

Fig. 3 is a detailed sectional View showing the bottom of the casings employed and how they function in carrying out the invention; and

Figf4 is a view similar to Fig.vl showing how the invention may be employed to extract sulfur from supposedly exhausted formations.

in general the invention consists in drilling the well so that the casings Awhich are inserted into the hole approach the sulfur formation and extend into it as shown in the drawings with a horizontal component such that substantial amounts of the sulfur in the deposit overlie this hole and the casings which are to beinserted in it throughout a major portion of the length thereof in the deposit and at an angle which is generally acute to the horizontal and is generally parallel to the lines of movement of the earth on subsidence caused by the sulfur mining operation so as to avoid shearing or" the casing on subsidence. The casings which are inserted through the earth and into the formation are concentric and are open at the bottom and as shown in the drawings for the major portion of their length in the deposit they underlie a substantial amount of sulfur in the deposit as distinguished from a vertical well in which the casing does not underlie any substantial portion of the sulfur in the deposit'. Hot water is introduced through one of the casings to melt the sulfur in the deposit both along the length of the casing which extends into the deposit and above the casing extending through the deposit so that the sulfur which can be thus melted will run down to the lower end of the casing where it may be extracted in the conventional manner through one of the casings. The initial introduction of the water into the casing melts the sulfur directly adjacent the casing and in that way forms a passageway down which the sulfur can proceed to the lower end of the casing. This passage also serves to permit the hot water after it has been discharged from the end of the casing to flow back up along the casing to view in section through the deposit showing how the inmelt and thus extract the sulfur in the deposit overlying the casing which sulfur will then run Idown to the lower end of the casing for extraction. The disposition of the casing in this manner in the deposit beneath substantial portions of the sulfur as opposed to the regular vertical casing leads to unexpectedly increased production and efficiency as pointed out below in that the amount of water required for given production is substantially halved and the production of sulfur per unit of water is substantially doubled. This increase in efficiency is so great that as pointed out below it is possible to work a field which has been, exhausted by vertical drilling and obtain sufficiently high yields of sulfur to justify the operation commercially.

In carrying out this method, it is possible to avoid the mechanical failures due to, subsidence and unexpectedly one is able to produce about 300 tons of sulfur per day with the expenditure of only 200 gallons per minute of 320 F. water as opposed to the use of 600 gallons per minute of 320 F. Water to produce the same tonnage in a vertically drilled well. Furthermore,` it is possible to extract up to 100,000 tons of sulfur from a given well as opposed to 4,000 tons of sulfur before exhaustion of a vertical well, all of which is accomplished without any complications resulting from subsidence of the surface earth and possible wrecking and loss of drilling and operating equipment. Y

ln Fig. l there is shown a typical well drilled in accordance with this invention. The sulfur formation, which is generally a limestone and sulfur formation, is indicated at l. The cap rock, which is usually a limestone formation, is indicated at 2. The overlying formation, indicated at 3, are usually unconsolidated consisting of sand, gravel, shale and boulders, while the surface, indicated at 4, is generally clay` ln the formation shown the sulfur is located at about 700 feet and the formation is approximately l25 feet in thickness.

The drilling site, which is indicated at 5, is located laterally from the lower end of the well a distance of about 800 feet.l The casings, which are indicated at 6, and which are the usual concentric casings which include an air line, extend downwardly and laterally, and at the lower portions thereof are at an angle acute to the horizontal and extend on a line substantially parallel to the line of lateral shift of the ground, which will occur on subsidence of the ground resulting from the mining operation.

ln Fig. 3 the detail of the. casing arrangement is shown. The outer casing is indicated at 7, the inner concentric casing at 8, which also carries an air line. The air line is not shown in detail since it is conventional.

ln this particular well the length of casing in the formation, which is only 125 feet deep, is approximately 400 feet.

The not water which is introduced at a temperature of 320 F., ows through the outer casing and out through the openings 9 in the outer casing. This water circulates as indicated by the upwardly-pointing arrows 19. lt tends to flow upward, outside of and adjacent to the casing, as indicated, since the Warm casing has tended to melt the sulfur in the formation and tends to create a stack effect at a pressure of about six pounds per square inch. The water melts the sulfur which flows downwardly, as indicated by the downwardly-pointing arrows 11, to the lower end of the casing, where in conventional manner it is carried by the introduction of air by the inner casing S.

As additional water is introduced into the well, it tends to rise. and to exhaust the sulfur not only along the casing, but also above the entire length of the casing in the formation and also in the area above and beyond the end of the casing the portion of the deposit from which the sulfur is extracted thus encompasses not only the inverted cone having its apex at. the outlet of the casing but also the sulfur of the deposit which overlies the portion of the casing which extends into the deposit and underlies this sulfur.

Because of the heating effect of the casing and because the water does not escape from the formation as readily as it can in vertical drilling operations, materially more sulfur is melted and extracted than in vertical operations, and as pointed out above, with a materially lower consumption of hot water and consequent saving of operating cost.

ln Fig. 4 the method is shown applied to anv exhausted sulfur formation which resulted from vertical drilling. The sulfur formation 161 has been partially exhausted, as indicated at H3. The cap rock 102 and the soil above ltl have subsided from the dotted-line position, indicated at 2.02, to the solid-line position. Water has collected at lid where the ground has subsided. The drilling site 1195 corresponds to thev side 5 in thev form of invention described above, and the casing 166 is the same. It will be noted that the lower portion of the casing has entered the sulfur formation at an angle actute to the horizonal and is in a position to reach and extract sulfur missed by the normal vertical mining operation.

in such an operation of a supposedly previously exhausted formation, it has been possible to extract as much as 34,000 tons of sulfur with a single well from a formation containing only about 4% sulfur with limestone.

Not only is it possible in using this method to malte more eihcient utilization of the heat and to get longer and greater production from single wells without mechanical failure, and to avoid the undesirable effects of surface subsidence at derrick location, but it is also possible to completely work a field with wells located on 20G-foot centers instead of Sil-foot centers.

The present invention may be employed in other ways Without departing from the spirit or essential, attributes thereof. lt is therefore desired that the present embodiments thereof be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

What is claimed is:

l. The method of extracting sulfur from underground deposits comprising drilling a hole through the ground and into the deposit from a point laterally displaced from the point of entry into the deposit and extending through the ground adjacent the deposit and into the deposit on a line generally parallel, to the direction of shift of the ground which will be caused, by exhaustion of said deposit and collapse ofthe ground thereabove and inserting concentric casings into said hole and melting the sulfur in said deposit along the length of said casings by introducing hot water through one of said casings and through the bottom thereof, whereby said hot water will flow baclt along the outside of vand adjacent to said casings and will rise into the deposit above the portion of said casings in said deposit and extracting molten sulfur through the other casing.

2. The method of extracting sulfur froml underground deposits comprising placing a pair of concentric casings through the ground above said deposit and into and through said deposit at an angle on a line' generally parallel to the direction of shift of the ground which will be caused by exhaustion of said deposit and collapse of the ground thereaboye, andy melting the sulfur in said deposit along the length of said casings in said deposit and above said casings by introducing hot water through the bottom of one of said casings into said sulfur deposit and extracting molten sulfur through the other casing.

3. rl'he method of extracting sulfur from an underground deposit comprising introducing a pair of concentric casings open 'at their lower ends into said deposit at an angle to the vertical and underlying substantial portions of said deposit, introducing hot water into one of said casings and thereby melting the sulfur directly adjacent said casings and creating a passage for water and molten sulfur in said deposit directly adjacent but outside said casings and introducing hot water into said deposit from the end of said casings into which water has been introduced and thereby extracting the sulfur from a portion of said deposit generally in the form of an inverted cone with its apex at the lower end of said casings by melting the sulfur in said conical portion of said deposit and also extracting sulfur from additional portions of said deposit other than said conical portion which overlies said casing in said deposit through the passage of hot water from the lower end of said casing into which water has been introduced and through the pas- Sage adjacent but outside said casings and into said additional portions of said deposit above said casings and thereby melting the sulfur in said additional portions of the deposit and removing the molten sulfur through the other of said casings.

4. The method of extracting sulfur from an underground deposit comprising introducing a pair of concentric casings open at their lower ends into said deposit at an angle to the vertical and underlying substantial portions of said deposit, introducing hot water into one of said casings and thereby melting the sulfur directly adjacent said casings and creating a laterally extending passage for water and molten sulfur in said deposit directly adjacent but outside said casings, and introducing hot water into said deposits from the open end of the casing into which hot water has been introduced and thereby extracting the sulfur from a portion of said deposit generally in the form of an inverted cone with its apex at the lower end of said casings by melting the sulfur in said conical portion of said deposit by said introduction of hot water into said deposit, and in addition extracting sulfur from additional portions of said deposit other than said conical portion which additional portions overlie said casing in said deposit by introducing hot water from said casing into which hot water has been introduced into said passage in said deposit directly adjacent but outside said casings and therethrough into said additional portions of said deposit and thereby melting the sulfur in said additional portions and removing the molten sulfur through the other of said casings, the angle of introduction of said casings being such as to place the casings under portions of said deposit other than the inverted conical portion of said deposit aforesaid and in addition thereto.

OTHER REFERENCES The Oil and Gas Journal, Feb. 5, 1948, page 69. 

1. THE METHOD OF EXTRACTING SULFUR FROM UNDERGROUND DEPOSITS COMPRISING DRILLING A HOLE THROUGH THE GROUND AND INTO THE DEPOSIT FROM A POINT LATERALLY DISPLACED FROM THE POINT OF ENTRY INTO THE DEPOSIT AND EXTENDING THROUGH THE GROUND ADJACENT THE DEPOSIT AND EXTENDING THROUGH LINE GENERALLY PARALLEL TO THE DIRECTION OF SHIFT OF THE GROUND WHICH WILL BE CAUSED BY EXHAUSTION OF SAID DEPOSIT AND COLLAPSE OF THE GROUND TEHERABOVE AND INSERTING CONCENTRIC CASING INTO SAID HOLE AND MELTING THE SULFUR IN SAID DEPOSIT ALONG THE LENGTH OF SAID CASINGS BY INTRO- 